Family sizes are shrinking around the world. In many countries, families are having fewer than two children.

Smaller families mean many children now grow up with fewer cousins. This is hard to imagine, as I come from a large extended family with 23 first cousins on one side and 25 on the other.

Sometimes when I can't sleep, I test my mental acuity (敏锐度) by trying to name all my relatives. Then in the morning I get up and wonder if I should make an appointment with a brain specialist.

Of course, almost all of those cousins have married and had children and now their children are having children.

With extended families growing so large and spreading so far, get-togethers have nearly become a thing of the past.

One of the last gatherings on my father's side was at the home of a cousin who has a place in the country on top of a hill. A tent was set up with long tables creaking (吱嘎作响)under the weight of fried chicken, potato salad and chocolate cake. A fishing hole waited nearby for the kids. Vehicles poured in from every direction, parking on the drive, the grass, wherever they could find a spot. There was talking and laughing and joking and food.

While such gatherings had grown infrequent, we were all happy to be together.

Although some of us had not seen one another since so-and-so's wedding or somebody's father's funeral, most people were still easy to recognize. Three sisters who sat together all had the same beautiful skin their mother had.

The cousin with bright blue eyes who raced her horse as a teenager still had bright blue eyes. An older cousin who gave me piano lessons when I was young and naughty seemed to have forgiven me.

We share a gene pool (基因库) of people who work hard and laugh often.

It was very dark when the last set of taillights (尾灯) disappeared into the night, . As we gathered our things, said our goodbyes and prepared to leave, a cousin called to me saying, " Don't forget where you come from".

I never could. And I'd never try.

It's commonly thought that boys perform better than girls in math and science. Researchers have challenged that stereotype (刻板印象) for a longtime, and a recent study, published in the journal Nature Communications in September, found a new way to attack it.

The study found that women are better than men at sustaining (维持)their performance on longer tests, including math and science.

Researchers Pau Balart, from the University of the Balearic Islands in Spain, and Matthijs Oosterveen from Erasmus University in the Netherlands, analyzed data collected every three years from 2006 to 2015. The data came from 74 countries and regions, for the Programme for International Student Assessment (PISA). This is a standardized test of 15-year-old students' performance in reading, math and science.

Their earlier results agreed with earlier findings that boys do better than girls in math and science. But when they compared the two groups' scores at different stages of the test, girls tended to perform more stably(稳定地) in math and science, while boys started getting fewer correct answers.

Although boys seemed to show advantages from the start in math and science, the authors wrote, "This finding suggests that longer tests shrink it in math and science, " according to Nature. To prove this, the researchers analyzed another database with over 400 math tests, which lasted longer than PISA's two hours. They found that, at least for math, the scoring gap between boys and girls decreased.

This isn't the observation of better test endurance (忍耐力) in women. Oxford University used to add an extra 15 minutes to its math and computer science exams. They found female students' scores improved.

Olga Shurchkov, an associate professor at Wellesley College in the US, told Newsweek: "This study is important because it provides cross-country evidence that suggests these gender (性别) gaps can be reduced. "

In her earlier study, she found that, given more time, women tended to be more careful and make fewer mistakes. They also were less likely to quit a task early. This also supports the finding of the present study.